Import a suitable font.Enable unicode when importing.
Add font to Settings → Editor Settings : Global/Font, Text Editor/Font.
Restart Editor.
Change controls font to imported one.
Update:
Maybe you can use Remap to change fonts automatically.
Also you can use TranslationServer’s methods get_locale and set_locale to get/set locale and load fonts based on it:
var loc = TranslationServer.get_locale()
if loc == "en" :
print("Locale is en")
var fnt = load("res://en.fnt")
get_node("button_start").add_font_override("font", fnt)
I was concerned about changing the fonts in the application not in the editor, depending on the detected language.